Method and system for spectral data analysis

ABSTRACT

Characteristics of proteins, peptides, and/or peptoids can be determined via two-dimensional correlation spectroscopy and/or two-dimensional co-distribution spectroscopies. Spectral data of the proteins, peptides, and/or peptoids can be obtained with respect to an applied perturbation. two-dimensional co-distribution analysis can be applied to generate an asynchronous co-distribution plot for the proteins, peptides, and/or peptoids to define the population of proteins in solution. In the two-dimensional asynchronous plot, a cross peak can be identified as correlating with an auto peak in the two-dimensional correlation synchronous plot associated with aggregation of the proteins, peptides, and/or peptoids. The two-dimensional asynchronous cross peak can be used to determine an order of a distributed presence of spectral intensities with respect to the applied perturbation. For example, for two wavenumbers v 1  and v 2 , the value of the cross peak corresponding to the two wavenumbers can indicate a presence of spectral intensity at v 1  relative to the presence of spectral intensity at v 2 .

RELATED APPLICATION

This application is a National Stage application under 35 U.S.C. 371 ofPCT International Application No. PCT/US2017/014338, filed Jan. 20,2017, which claims the benefit of U.S. Provisional Application No.62/281,630, filed Jan. 21, 2016, the entirety of which is herebyincorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

This invention was made with Government support under Award Nos. 1632420and 1447918 awarded by the National Science Foundation. The governmenthas certain rights in this invention.

BACKGROUND

Protein aggregation phenomena are prevalent throughout the industrialbioprocess. Proteins are expensive to express, isolate, and purify dueto their complex physical-chemical characteristics. Aggregation isconsidered a primary mode of protein degradation, at times leading toimmunogenicity, anti-drug antibody response (ADA) in patients and a lossof efficacy. The detection and determination of protein aggregates is amajor objective in the biopharmaceutical industry and other areas ofscientific research. The formation of protein aggregates is important inindustrial applications because they can significantly affect theproduction of protein therapeutics (i.e., biologics or biosimilars),effectively lowering the production yields.

SUMMARY

The subject technology is illustrated, for example, according to variousaspects described below. Various examples of aspects of the subjecttechnology are described below. These are provided as examples and donot limit the subject technology.

Aspects of the subject technology provide a method for determiningaggregation in protein, peptide and/or peptoid formulation, in solutionor lyophilized state without the use of probes or additives.

According to aspects of the subject technology, the protein sample isspectroscopically analyzed and the spectral data analyzed using theestablished method to determine viability of the protein sample. Themethod and/or portions thereof can be fully automated and be used forthe determination of the mechanism of aggregation.

According to aspects of the subject technology, methods described hereincan be applied to membrane proteins, hydrophilic proteins, peptides andpeptoids as a single component or in binary or ternary mixtures withother peptides or lipid mixtures. When in mixtures, one of thecomponents must be isotopically labeled to allow for the simultaneousdetection of each component.

Aspects of the subject technology allow flexibility of the samplepreparation, its potential for automation, and data analysis which haveproven its utility for pharmaceutical protein formulation.

According to aspects of the subject technology, methods described hereincan be applied to any protein, peptide or peptoid sample in severalenvironments, aqueous or lipidic. Methods described herein can be usedqualitatively and/or quantitatively for determining protein aggregation.Data analysis is performed through which the mechanism of proteinaggregation is determined and the stability and/or viability of theprotein, peptide or peptoid can be determined.

According to one aspect of the subject technology, the method involvestransmission Fourier transform infrared (“FT-IR”) and/or attenuatedtotal reflectance (“ATR”) spectroscopy, quantum cascade laser microscopy(“QCL”), two-dimensional correlation spectroscopy (“2DCOS”), and/ortwo-dimensional co-distribution spectroscopy (“2DCDS”) for the analysisof these proteins, peptides or peptoids. According to aspects of thesubject technology, spectral data can be obtained using any suitablemethod and equipment, such as a FT-IR spectrometer, FT-IR microscope,QCL spectrometer or QCL microscope. In aspects of the subjecttechnology, it is preferred to obtain spectral data using a QCLmicroscope.

Methods, systems, and instructions for processing data representing acharacteristic of proteins, peptides, and/or peptoids can include:obtaining spectral data of the proteins, peptides, and/or peptoids withrespect to an applied perturbation; applying two-dimensionalco-distribution analysis to generate an asynchronous co-distributionplot for the proteins, peptides, and/or peptoids; identifying in theasynchronous co-distribution plot a cross peak that correlates with anauto peak associated with aggregation of the proteins, peptides, and/orpeptoids; and using the cross peak to determine an order of adistributed presence of spectral intensities with respect to the appliedperturbation.

Using the cross peak can include: determining, for two wavenumbers v₁and v₂, whether the cross peak corresponding to the two wavenumbers hasa positive value; and when the cross peak has a positive value,determining that a presence of spectral intensity at v₁ is distributedwithin an interval of the applied perturbation that is lower than aninterval within which a presence of spectral intensity at v₂ isdistributed. Using the cross peak can include: determining, for twowavenumbers v₁ and v₂, whether the cross peak corresponding to the twowavenumbers has a negative value; and when the cross peak has a negativevalue, determining that a presence of spectral intensity at v₂ isdistributed within an interval of the applied perturbation that is lowerthan an interval within which a presence of spectral intensity at v₁ isdistributed.

Operations can include: applying the two-dimensional correlationanalysis to generate a synchronous plot for the proteins, peptides,and/or peptoids; identifying, in the synchronous plot, synchronous peaksassociated with aggregation of the proteins, peptides, and/or peptoids;and using the synchronous peaks to determine a degree of overlap ofdistribution patterns for spectral intensities with respect to theapplied perturbation.

Operations can also include: applying two-dimensional correlationanalysis, generating a synchronous plot and an asynchronous plot for theproteins, peptides, and/or peptoids; identifying, in the synchronousplot, positive cross peaks that correlate with auto peaks associatedwith aggregation of the proteins, peptides, and/or peptoids; and usingidentified peak intensities of the spectral data to determine an amountof aggregation of the proteins, peptides, and/or peptoids.

The amount of aggregation of the proteins, peptides, and/or peptoids canbe compared to an order of a distributed presence of spectralintensities with respect to the applied perturbation. Regions ofinterest can be recognized for discrimination of particulates andsolution. A size and a number of particulates can be determined toascertain population distribution of the particulates. The spectral datacan be analyzed to verify signal-to-noise ratio, perform a baselinecorrection, determine water vapor content, and/or determine signalintensity within a spectral region. Covariance or dynamic spectral datacan be generated based on perturbation of a sample. Changes, comprisingpeak intensities, can be correlated in the spectral data that arein-phase with one another as obtained in the synchronous plot. Elementsthat change in the spectral data can be determined. An overall greatestintensity change in the spectral data can be determined. An overallsmallest intensity change in the spectral data can be determined. Aminimum number of underlying spectral contributions in a band,performing curve fitting analysis, and a secondary structure compositionof a sample can be determined. Changes, comprising peak intensities, canbe correlated in the spectral data that are out-of-phase from oneanother as obtained in the asynchronous plot.

Additional features and advantages of the subject technology will be setforth in the description below, and in part will be apparent from thedescription, or may be learned by practice of the subject technology.The advantages of the subject technology will be realized and attainedby the structure particularly pointed out in the written description andclaims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the subject technology asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide furtherunderstanding of the subject technology and are incorporated in andconstitute a part of this description, illustrate aspects of the subjecttechnology and, together with the specification, serve to explainprinciples of the subject technology.

FIGS. 1A, 1B, and 1C show results of orthogonal bioanalytical techniquesused to determine protein aggregation according to some aspects of thesubject technology. FIG. 1A shows a result of size exclusionchromatography (“SEC”). FIG. 1B shows a result of differential scanningcalorimetry (“DSC”). FIG. 1C shows a result of dynamic light scattering(“DLS”).

FIG. 2 shows a flowchart indicating different phases of a methodaccording to some aspects of the subject technology.

FIG. 3 shows results of a multi-stage analysis.

FIG. 4 shows a diagram of an exemplary computing system according tosome aspects of the subject technology.

FIG. 5 shows a flowchart indicating operations of an exemplary methodaccording to some aspects of the subject technology.

FIG. 6 shows a flowchart indicating operations of an exemplary methodaccording to some aspects of the subject technology.

FIG. 7 shows results of a multi-stage analysis.

FIG. 8A shows comparison of ADC fragment candidate amino acid sequencesfor developability assessment. ADC fragment 0 (“ADC0”; SEQ ID NO:1) isthe full-length fragment containing an additional 7 amino acids(APELLGG; SEQ ID NO:2) at the N-terminal end. ADC fragment 1 (“ADC1”;SEQ ID NO:3) is truncated at the N-terminal end and like the topfragment contains 1 disulfide bridge. ADC fragment 2 (“ADC2”; SEQ IDNO:4) has two point mutations (L5C/K97C) when compared with ADC fragment1, thus adding an additional disulfide-bridge to stabilize the ADCfragment 2.

FIG. 8B shows a Richardson ribbon model comprised mainly of β-sheets,β-turns and hinges as well as 2 short helices within the ADC fragment.Shows are the N-terminal end, the C-terminal end, the 3 Arg at positions25, 62 and 71, the neighboring Pro residues at positions 27 and 61, andthe disulfide bond Cys₃₁ and Cys₉₁. These 3 arginine residues serve asinternal probes for ADC's.

FIGS. 9A and 9B show size and identify of aggregates. FIG. 9A shows QCLinfrared spectral overlay for ADC0 and ADC1. FIG. 9B shows plots for 24and 28° C., respectively. The ADC fragments were all fully H→Dexchanged. Moreover, the amide I′ band maximum at 24° C. corresponds toaggregated ADC1, while at 28° C. the maximum corresponds to the ADC1 inD₂O solution.

FIG. 10 shows results of a co-distribution analysis. The aggregationmechanism involved the arginine residues and selected anti-parallelβ-sheets and β-turn within the protein. Therefore, this analysisprovides the region of the protein that is causing the aggregation.

FIG. 11A shows QCL microscope images and FIG. 11B shows associated QCLspectra of ADC fragment 2 in 15% sucrose. This can be used to validatethe presence and quantity of both the excipient and the proteincandidate.

FIGS. 12A, 12B, and 12C show QCL spectral results obtained for ADC2 inHEPES at pH 6.6 in the presence of NaCl and varying amounts of sucrose(FIG. 12A: 15% sucrose, FIG. 12B: 30% sucrose, and FIG. 12C: 60%sucrose) as excipient at 26° C. within the spectral region of 1400-1800cm⁻¹. These results demonstrate the extent to which the quantitativeanalysis can be performed, providing vital information otherwisedifficult to obtain. The stability and conformation of the protein canbe confirmed under the desired excipient conditions, while alsopermitting the determination of concentration of the protein of interestand its excipient in solution. Furthermore, no aggregate species wasobserved for ADC2 under these conditions.

FIG. 13 shows results of normal distribution analysis performed for 43experiments using the QCL microscope under varying conditions. The QbDexperimental setup was such that 324 spectral data were analyzedrepresenting the evaluation of ADC fragment 2 in the presence of varyingamounts of NaCl, sucrose and varying ratios of both excipients (i.e.,NaCl & sucrose).

FIG. 14 shows results of DOE stepwise model fitting, includingpredictive profiles for the ADC2 QCL microscopy spectral data using thesecond best fit model (AIC model).

FIG. 15 shows results of DOE stepwise model fitting, includingpredictive profiles for ADC2 QCL microscopy spectral data using the bestfit model (BIC model). The results suggest 18.5% sucrose as the bestexcipient for ADC2 at near room temperature conditions.

FIGS. 16A and 16B show 2D IR correlation analysis plots (FIG. 16A:synchronous, FIG. 16B: asynchronous) for ADC fragment 2 in the presenceof HEPES and 15% sucrose within a temperature range of 26-28° C. Theamide I′ and side chain bands studied in the spectral region of1720-1500 cm⁻¹. The synchronous plot (FIG. 16A) ADC2 was observed tohave mainly β-sheet and β-turn secondary structure with no presence ofaggregate species.

FIG. 17 shows the sequential order of events for ADC fragment 2 in 50 mMHEPES, 150 mM NaCl, 3 mM KCl and 15% sucrose at pH 6.6 and a temperatureof 26° C. used to confirm the role of sucrose in stabilizing theprotein.

FIGS. 18A and 18B show 2D IR co-distribution analysis plots (FIG. 18A:synchronous, FIG. 18B: asynchronous) ADC2 in HEPES and 15% sucrose asexcipient in the temperature range of 26-28° C. Side chains along withthe π-helix and β-turns (hinge loops) were perturbed at lowtemperatures.

FIG. 19 shows representative curve-fit analysis for ADC Fragment 2 inD₂O using the band assignments generated from the 2D IR correlationanalysis and for which 80.4+/−1.1% of the protein was determined tocomprise β-structure (see also Tables 2 and 3).

FIG. 20A shows overlaid spectra showing the amide I, II and III bandsfor NIST mAb at 50 mg/mL in the MID IR spectral region of 1750-1400 cm⁻¹acquired within the temperature range of 24-60° C. in H₂O.

FIGS. 20B and 20C show 2D IR correlation analysis plots (FIG. 20B:synchronous, FIG. 20C: asynchronous) for the sample of FIG. 16A.

FIG. 21A shows overlaid spectra showing both the amide I and II bandsfor NIST mAb at 50 mg/mL in the MID IR spectral region of 1750-1500 cm⁻¹acquired within the temperature range of 24-60° C. in H₂O.

FIGS. 21B and 21C show 2D IR correlation analysis plots (FIG. 21B:synchronous, FIG. 21C: asynchronous) for the sample of FIG. 21A.

FIG. 22 shows the sequential order of events for NIST mAb at 50 mg/mL inH₂O under thermal stress within the temperature range of 24-60° C.

FIG. 23 shows an asynchronous 2D IR co-distribution analysis plot forNIST mAb at 50 mg/mL in H₂O under thermal stress within the temperaturerange of 24-60° C.

FIGS. 24A, 24B, 24C, and 24D show reproductions of the plots of FIGS.21A, 21B, 21C, and 22, respectively, with the addition of brokenvertical lines crossing the auto peaks of the synchronous plot 2D IRcorrelation analysis plots (FIG. 24B).

FIG. 25A shows overlaid spectra showing both the amide I and II bandsfor BSA at 40 mg/mL in the MID IR spectral region of 1750-1500 cm⁻¹acquired within the temperature range of 24-60° C. in H₂O.

FIGS. 25B and 25C show 2D IR correlation analysis plots (FIG. 25B:

-   -   synchronous, FIG. 25C: asynchronous) for the sample of FIG. 25A.

FIG. 26 shows the sequential order of events for BSA 40 mg/mL in H₂Ounder thermal stress (24-60° C.).

FIG. 27 shows an asynchronous 2D IR co-distribution analysis plot forBSA 40 mg/mL in H₂O under thermal stress within the temperature range of24-60° C. and spectral region of 1750-1380 cm⁻¹.

FIG. 28A shows overlaid spectra showing both the amide I and II bandsfor NIST mAb/BSA (1:2, mol ratio) mixture in the spectral region of1750-1500 cm⁻¹ acquired within the temperature range of 24-60° C. inH₂O.

FIGS. 28B and 28C show 2D IR correlation analysis plots (FIG. 28B:synchronous, FIG. 28C: asynchronous) for the sample of FIG. 28A.

FIG. 29A shows overlaid spectra showing both the amide I and II bandsfor Lysozyme at 600 mg/mL in the spectral region of 1750-1500 cm⁻¹acquired within the temperature range of 24-60° C. in H₂O.

FIGS. 29B and 29C show 2D IR correlation analysis plots (FIG. 29B:synchronous, FIG. 29C: asynchronous) for the sample of FIG. 29A.

FIG. 30 shows the sequential order of events for Lysozyme at 600 mg/mLin H₂O under thermal stress (24-60° C.).

FIG. 31 shows an asynchronous 2D IR co-distribution analysis plot forLysozyme at 600 mg/mL in H₂O under thermal stress within the temperaturerange of 24-60° C. and spectral region of 1750-1500 cm⁻¹.

FIG. 32 shows an exemplary diagram of a computing system.

DETAILED DESCRIPTION

In the following detailed description, specific details are set forth toprovide an understanding of the subject technology. It will be apparent,however, to one ordinarily skilled in the art that the subjecttechnology may be practiced without some of these specific details. Inother instances, well-known structures and techniques have not beenshown in detail so as not to obscure the subject technology.

Proteins are large organic compounds made of amino acids arranged in alinear chain and joined together by peptide bonds between the carboxyland amino groups of adjacent amino acid residues. Most proteins foldinto unique 3-dimensional structures. The shape into which a proteinnaturally folds is known as its native state. Although many proteins canfold unassisted, simply through the chemical properties of their aminoacids, others require the aid of molecular chaperones to fold into theirnative states. There are four distinct aspects of a protein's structure:

-   -   Primary structure: the amino acid sequence.    -   Secondary structure: regularly repeating local structures        stabilized by hydrogen bonds. Because secondary structures are        local, many regions of different secondary structure can be        present in the same protein molecule.    -   Tertiary structure: the overall shape of a single protein        molecule; the spatial relationship of the secondary structures        to one another.    -   Quaternary structure: the shape or structure that results from        the interaction of more than one protein molecule, usually        called protein subunits in this context, which function as part        of the larger assembly or protein complex.

Proteins are not entirely rigid molecules. In addition to these levelsof structure, proteins may shift between several related structureswhile they perform their biological function. In the context of thesefunctional rearrangements, these tertiary or quaternary structures areusually referred to as “conformations,” and transitions between them arecalled conformational changes.

Protein aggregation is characterized as a misfolded, rigid proteingrouping which is considered a prevalent phenomenon throughout theindustrial bioprocess. Aggregation is considered a primary mode ofprotein degradation, often leading to immunogenicity of the protein anda loss of bioactivity. Protein aggregation is of critical importance ina wide variety of biomedical situations, ranging from abnormal diseasestates, such as Alzheimer's and Parkinson's disease, to the production,stability and delivery of protein drugs. Protein aggregation, whichcould be amorphous or fibrillar in nature, can start by one of twodifferent mechanisms: A) self-aggregation, in which the partially-foldedintermediates are the immediate precursors for aggregation, and B)hetero-aggregation, in which the aggregation of one protein is mediatedby another protein.

The formation of protein aggregates is critical in industrialapplications, because it can highly affect the production ofprotein-based drugs or commercial enzymes, greatly lowering theproduction yields. The biologics and biosimilar industry is involved inthe research, development, and manufacturing of complex drugs thatinclude protein therapeutics. The research and development efficiencycan be undesirably low, which increases costs of drug development due tothe high attrition rate of protein therapeutics. The cost of proteintherapeutic development is significantly impacted by late stage failure.One way to lower research and development costs is to perform a seriesof evaluations of the protein therapeutic candidate early in theresearch and development phase. By performing the characterization ofthe therapeutic protein under varying formulation conditions andstressors early in the research and development phase, a predictiveprofile of the therapeutic candidate is generated to assess the risk ofprotein aggregation. This approach has been defined as a developabilityassessment. This assessment can provide important information fordecision making, such as selecting protein therapeutic candidates forfurther development. When protein aggregation occurs the proteintherapeutic typically has decreased efficacy and can elicit an immuneresponse. In severe cases, such an immune response can be fatal.

Several methods have been proposed in the past for the determination ofaggregates in mixtures. These prior methods are either designed for aparticular protein or peptide and/or require the addition of a foreignprobe, and thus, do not represent a generalized method with a universalapplication to a class of biological molecules. Several spectroscopictechniques have been used, like UV-Vis spectroscopy with the aid ofprobes, fluorescence spectroscopy also using internal or exogenousprobes. Similarly, near UV circular dichroism (“CD”) has been used butis limited to the detection of the aggregate in its immediate vicinity,and nuclear magnetic resonance (“NMR”) could be used to detect proteinaggregation by the appearance of band broadening. Sedimentation analysiscould also be used to identify the extent of oligomerization as long asthe protein of interest has a large enough molar extinction coefficient.Chromatographic techniques such as size exclusion could also detect thepresence of protein aggregates. But these techniques may require the useof exogenous probes, large amounts of protein, are time consuming andnone allow for the determination of the mechanism of aggregation.

The problem of protein aggregation is complex and frequently involvesseveral different chemical and/or computational processes, which aredifficult to discern. Aggregation may be stress induced and involvephysical or chemical changes such as agitation, oxidation, deaminationand temperature changes. Even a slight change in pH, salt conditions,protein concentration or formulation conditions can also induce proteinaggregation. Again, aggregation leads to lower yields in production,loss of efficacy of the protein therapeutic, and safety concerns inrelation to immunogenicity risks. Currently available techniques toassess aggregation do not address all of the factors that are involvedin the process, such as the size, identity, mechanism and extent ofaggregation, and stability of the protein therapeutic in solution.Several techniques have been developed to address the size of theaggregate or particulate, yet they do not determine the identity. Othertechniques can determine the size and the identity of aggregates, butcannot determine the extent of aggregation. The amino acid side chainspresent in a protein are important contributors to the stability ofproteins. Yet, the relationship between the weak chemical interactionsobserved in side chains and the stability of the secondary structure ofa protein can not been determined using routine bench instrumentation ina high throughput process.

The stability of the protein therapeutic is also critical for drugdevelopment, and cannot be fully characterized by simply identifying thethermal transition temperature of the protein. A greater level ofunderstanding is needed to understand and address the stability ofprotein therapeutics. For example it would be beneficial tounderstand 1) the relative stability of the domains within the proteinof interest, 2) how the amino acid side chains contribute to thestability the domains, 3) whether the amino acid side chains areinvolved in the aggregation mechanism, and 4) if an excipient canstabilize weak interactions (e.g., in amino acid side chains) within thecritical regions in specific domains of the protein therapeutic. Thereis a gap in understanding parameters that are important for determiningthe mechanism of protein aggregation.

When currently commercially available techniques are used orthogonally,differences in the sensitivity of the available techniques is a concern.In general, such techniques focus on determining the size, purity andstability of the protein therapeutic, and evaluate the presence orabsence of protein aggregates or particulates in a formulation, toachieve lot-to-lot consistency.

There is a need for technology that can be used to better assess thedevelopability of protein therapeutics, and for the comparabilityassessments needed to maintain and ensure product integrity, efficacyand safety. Such a process would need to be recognized as sufficient toensure product integrity, efficacy and safety by the Food and DrugAdministration (“FDA”) Center for Drug Evaluation (“CDER”) division andother relevant regulatory bodies.

Solution to the protein aggregation problem for the Biopharma industrywould lead to: (1) decreased R&D costs, (2) increased product yieldsthus ensuring its supply and demand, (3) lower risks of withdrawals, (4)increased FDA approval rates (5) reduce the time-to-market and (6) inturn increase its valuation. Also, the pipeline of new proteintherapeutics is poised to address the treatment of cancer and chronicdiseases such as rheumatoid arthritis, Chron's disease andneurodegenerative disorders, among others, thus improving the quality oflife of patients.

Aspects of the subject technology provide a fast, accurate, andreproducible technique to determine the size, identity, mechanism, andextent of aggregation and the stability of a protein therapeutic, orother chemical, in a single experiment. Aspects of the subjecttechnology address comparability assessment of different proteintherapeutic candidates and developability assessment of proteintherapeutic candidates. The data can be used for classification andchemical characterization of proteins, polymers, organic materials,inorganic materials for discovery, research and development in pilotscale or manufacturing or for quality control and assurance purposes.Also for the stability assessment during storage and delivery of theprotein therapeutic.

The computational methods and systems described herein providesignificant improvements over existing analysis for proteins. Thecomputational methods and systems described herein generates and storesdata in forms that facilitate efficient and meaningful analysis withoutrequiring the use of several pieces of equipment. Accordingly, thecomputational methods and systems described herein can improve theefficiency of spectral data analysis for evaluation of candidate drugs.

Aspects of the subject technology include the use of two-dimensionalcorrelation spectroscopy (“2DCOS”) and two-dimensional co-distributionspectroscopy (“2DCDS”) to provide essential information towards theextent and mechanism of aggregation of a protein therapeutic. Themethods described herein can include analysis of the side chain modes asinternal probes, offering information that confirms the stability of thestructural motif or domain within proteins. The methods described hereinhave been shown to be useful in High Throughput-Developability andComparability Assessment (“HT-DCA”) via a Design of Experiment (“DOE”)approach that complied with Quality by Design (“QBD”).

According to some embodiments, systems and methods described herein canalso be used to determine protein-protein interactions (“PPI's”) orprotein-macromolecules (protein-lipid interactions, protein DNA orprotein-RNA interactions or protein drug interactions). Also, systemsand methods described herein can be used for the analysis of organicsolutions, polymers, gels, nanostructures or small liquid crystals, etc.

FIG. 1A shows a result of size exclusion chromatography (“SEC”), FIG. 1Bshows a result of differential scanning calorimetry (“DSC”), and FIG. 1Cshows a result of dynamic light scattering (“DLS”). These techniques canlead to determining the size, identity and extent of aggregation, butnone can define the mechanism of aggregation. Understanding themechanism of aggregation is fundamental to developing a protein drugthat will ensure its potential to act as intended with little or no riskof immunogenicity.

According to some embodiments, for example as shown in FIG. 2, samplesfrom different parts of a bioprocess, which could be aqueous orlyophilized, are monitored by Fourier Transform Infrared (ATR ortransmission) spectroscopy (“FT-IR”) and analyzed using 2DCOS in orderto search for aggregates. Other types of analysis can be employed, suchas Raman spectroscopy, Quantum Cascade Laser absorption, synchrotronsource Fourier transform infrared microscopy, and/or combinationsthereof. If aggregates are found, an evaluation procedure that mightinclude comparing the results against an established database can bestarted and as a result the protocol used in the bioprocess can bemodified or changed. FT-IR spectroscopy allows for a high degree offlexibility and speed in the determination of protein aggregates, withlimited manipulation, and without the use of exogenous probes. Anexemplary method can include FT-IR spectroscopy combined with the 2DCOS,which allows for the determination of the presence of aggregates, thedetermination of the mechanism of aggregation, allowing for correctionin the pipeline manufacturing process of the protein to once againgenerate viable protein. Another exemplary method can include QuantumCascade Laser microscopy combined with the 2DCOS, which allows for thedetermination of the presence of aggregates, the determination of themechanism of aggregation, allowing for correction in the pipelinemanufacturing process of the protein to once again generate viableprotein. In addition, the thermal transition of the protein can also bedetermined and a 2DCOS plot generated to compare with the establishedviable protein, allowing for quality control, stability, and viabilityof the desired protein product. Furthermore, the ease of samplepreparation and data analysis allows for the automation of this method.

FT-IR spectroscopy is sensitive to conformational changes andaggregation. This technique allows for qualitative and quantitativeanalysis of the extent of protein, peptide and peptoid aggregation. Theuse of 2DCOS allows for further analysis and provides mechanisticinformation related to the aggregation process. The method mayincorporate one or more of the following techniques: Transmission FT-IRSpectroscopy, Attenuated Total Reflectance (“ATR”) FT-IR Spectroscopy,2DCOS analysis, and/or 2DCDS analysis.

In Transmission FT-IR microscopy or QCL microscopy, sample preparationcan involve the use of pure protein, peptide or peptoid, in theappropriate buffer. The sample can be lyophilized and re-suspended inD₂O. The protein solution can be applied between a slide and cover andsealed to prevent solvent evaporation. The slide can be set in a slideholder. A similar procedure is used for a reference using theappropriate buffer (PBS or HEPES). A temperature probe located in closecontact with the slide is used to register the temperature of thesample. A temperature gradient over time can be used and the acquiredspectral data is received automatically through a thermocoupleinterface. During the spectral analysis the full width at half height(FWHH) of the amide I band can be determined as a function oftemperature to establish the transition temperature.

Attenuated Total Reflectance (ATR) FT-IR Spectroscopy can be used forhydrogen/deuterium exchange studies, titration experiments and thedetermination of the orientation of reconstituted membrane proteins. Inthis method the protein can be fully exchanged by repeatedlyophillization and redissolving the sample in D₂O. The fully exchangedprotein sample and buffer can be spread as a film independently wherethe buffer is considered as the reference. Typically, a protein samplein D₂O is spread onto the ATR crystal and allowed to dry, using a dryair purge. The subsequent spectrum would be representative of theprotein sample and if present, the aggregated form of the protein.

According to some embodiments, spectral data can be generated by anysuitable method, such as one or more of the above-described methods. Amolecule to be analyzed can be provided in solution with a solute, suchas water or D₂O, if desired. The concentration of the molecule to beanalyzed in solution is preferably with a range that provides a strongsignal from the molecule relative to any signal from the solute (e.g.,water) or other components of the sample (i.e., a suitable signal tonoise ratio), which can facilitate further analysis as described herein.Typically the concentration of a protein or peptide molecule that willprovide a desired signal-to-noise ratio is related and proportional tothe size of the protein or peptide. Preferred concentrations provideadequate signal-to-noise ratio for analysis. For example, as describedfurther herein, the sample can facilitate analysis of the spectra forthe molecule of interest without the need to subtract the spectraattributable to the solute (e.g., water or D₂O) or other components ofthe sample. For example, for an IgG or other protein of about 150 kD,the sample can contain the protein at a concentration of from about 50mg/mL to about 150 mg/mL. The amount of protein can be varied from thisrange proportionately to the size of the protein of interest, forexample, BSA which is about 67 kD can be analyzed in solution at aconcentration of about 25 mg/mL to about 75 mg/mL. The sample can beprovided in a cell having a path length. The path length can be longer(e.g., 30-50 μm, preferably about 40 μm) for D₂O and shorter (e.g., 4-12μm) for water.

According to some embodiments, spectral analysis can be performed instages, for example as illustrated in FIG. 3. The process illustrated inFIG. 3 can include stages performed as at least part of the “2DCOS/2DCDSanalysis” stage illustrated in FIG. 2.

According to some embodiments, the protein sample is perturbed(thermally, chemically, pressure, or acoustics) inducing a dynamicfluctuation in the vibrational spectrum. In stage 310, raw spectra datacan be collected and/or analyzed. The spectral data can be acquired atregular temperature intervals and in a sequential manner. According tosome embodiments, the data can be baseline corrected.

According to some embodiments, the spectral data can be used todetermine the existence of the aggregated form of the protein, peptideor peptoid. For this, the first spectrum is subtracted from thesubsequent spectra to generate the dynamic spectra. In stage 320,covariance (difference) spectra can be generated by subtraction of thefirst spectrum (24° C.) from all subsequent spectra. Consequently, thecovariance (difference) spectra contains positive and negative peaks;also referred as in- and out-of-phase from one another.

Notably the process described herein does not require the manualsubtraction of water or other reference (e.g., solute) from spectraldata. Such manual subtraction is a highly subjective step often incurredin protein spectral analysis. Instead, the process described hereingenerates the difference spectral data set based on the perturbation ofthe sample of interest. The output thereof can then be used for furtheranalysis. By subtracting the first spectrum which has the overlappingwater band along with the amide I band from all subsequent spectra, thespectral contributions of water are automatically subtracted.

In stage 330, a 2D IR correlation technique can be applied to generate asynchronous plot (stage 340) and an asynchronous plot (stage 350). Forexample, the spectral data can be fast Fourier transformed (“FFT”) togenerate the complex matrix from which an intensity matrix is obtainedthrough the cross correlation product the synchronous and asynchronousplots are generated. The techniques for generating these plots will bediscussed in greater detail herein.

The synchronous plot represents the intensity changes that occur duringthe perturbation. On the diagonal of this plot are the peaks or bands(known as auto peaks) that changed throughout the spectrum. Off thediagonal are the cross peaks which show the correlation between the autopeaks, that is, the relationship between the secondary structure changesobserved. The synchronous plot can be used to relate the in-phase peakintensity changes or shifts.

In synchronous correlation spectrum, auto peaks at diagonal positionsrepresent the extent of perturbation-induced dynamic fluctuations ofspectral signals. Cross peaks represent simultaneous changes of spectralsignals at two different wavenumbers, suggesting a coupled or relatedorigin of intensity variations. If the sign of a cross peak is positive,the intensities at corresponding wavenumbers are increasing ordecreasing together. If the sign is negative, one is increasing, whilethe other is decreasing.

The asynchronous plot contains only cross peaks which are used todetermine the order of events and thus the mechanism of aggregation ofthe protein. The asynchronous plot can be used to relate theout-of-phase peak intensity changes or shifts.

In asynchronous correlation spectrum, cross peaks develop only if theintensity varies out of phase with each other for some Fourier frequencycomponents of signal fluctuations. The sign of a cross peak is positiveif the intensity change at wavenumber v₂ occurs before wavenumber v₁.The sign of a cross peak is negative if the intensity change atwavenumber v₂ occurs after wavenumber v₁. The above sign rules arereversed if the same asynchronous cross peak position translated to thesynchronous plot falls in a negative region (Φ(v₁, v₂)<0).

The 2D IR correlation enhances the spectral resolution of the underlyingpeaks of broad bands such as the amide I and II bands by spreading thepeaks in two dimensions. These plots are symmetrical in nature, and fordiscussion purposes reference will be made to the top triangle foranalysis. The synchronous plot (shown at 340) contains two types ofpeaks: (a) auto peaks that are positive peaks on the diagonal and (b)cross peaks that are off-diagonal peaks that can be either positive ornegative. The asynchronous plot (shown at 350) is comprised exclusivelyof cross peaks that relate the out-of-phase peaks. As a result this plotreveals greater spectral resolution enhancement. The following rules canapply to establish the order of molecular events:

-   -   I. If the asynchronous cross peak, v₂, is positive, then v₂ is        perturbed prior to v₁ (v₂→v₁).    -   II. If the asynchronous cross peak, v₂, is negative, then v₂ is        perturbed after v₁. (v₂←v₁).    -   III. If the synchronous cross peak (off-diagonal peaks, not        shown in FIG. 3) are positive, then the order of events are        exclusively established using the asynchronous plot (rules I and        II).    -   IV. If the synchronous plot contains negative cross peaks and        the corresponding asynchronous cross peak is positive, then the        order is reversed.    -   V. If the synchronous plot contains negative cross peaks and the        corresponding asynchronous cross peak is negative, then the        order is maintained.

The order of events can be established for each peak observed in the v₂axis. A table can be provided summarizing the order for each event. Instage 360, a sequential order of events plot is generated using thetable summarizing the order of each event. On top of each step (event)is the spectroscopic information of the cross peak, v₂, while on thebottom of each step is the corresponding peak assignment or thebiochemical information for each event in the order in which they areperturbed as a function of temperature. Examples are provided herein.

Two-dimensional correlation spectroscopy (“2DCOS”) analysis can be usedto resolve complex bands, such as the amide I band. An example of 2DCOSanalysis is described in U.S. Pat. No. 8,268,628, hereby incorporatedherein by reference. The skilled artisan's attention is called to IsaoNoda, “Two-dimensional co-distribution spectroscopy to determine thesequential order of distributed presence of species”, Journal ofMolecular Structure, Vol. 1069, pp. 51-54, which describes algorithmssuitable for use in 2DCOS analysis.

A summary of the development of 2DCOS is as follows. A discretelysampled set of spectra A(v_(j), t_(k)) can be obtained for a systemmeasured under the influence of an external perturbation, which induceschanges in the observed spectral intensities. The spectral variablev_(j) with j=1, 2, . . . , n may be for example wave-number, frequency,scattering angle, etc., and the other variable t_(k) with k=1, 2, . . ., m represents the effect of the applied perturbation, e.g., time,temperature, and electrical potential. Only the sequentially sampledspectral data set obtained during the explicitly defined observationinterval between t₁ and t_(m) will be used for the 2DCOS analysis. Forsimplicity, wavenumber and time are used here to designate the twovariables, but it is understood that use of other physical variables isalso valid.

Dynamic spectrum used in 2D correlation spectroscopy is explicitlydefined as

$\begin{matrix}{{\overset{\_}{A}\left( {v_{j},t_{k}} \right)} = \left\{ \begin{matrix}{{A\left( {v_{j},t_{k}} \right)} - {\overset{\_}{A}\left( v_{j} \right)}} & {{{for}\mspace{14mu} 1} \leqslant k \leqslant m} \\{0\mspace{160mu}} & {{otherwise}\mspace{40mu}}\end{matrix} \right.} & (1)\end{matrix}$where Ā(v_(j)) is the spectrum of the reference state of the system. Inthe absence of the a priori knowledge of the reference state, thereference spectrum can also be set as the time-averaged spectrum overthe observation interval between t₁ and t_(m).

$\begin{matrix}{{\overset{\_}{A}\left( v_{j} \right)} = {\frac{1}{m}{\sum\limits_{k = 1}^{m}\;{A\left( {v_{j},t_{k}} \right)}}}} & (2)\end{matrix}$With this specific choice of the reference spectrum, the portion ofdynamic spectra within the observation interval essentially becomesequivalent to the mean-centered spectra. Synchronous and asynchronous 2Dcorrelation spectra Φ(v₁, v₂) and Ψ(v₁, v₂), are given by

$\begin{matrix}{{\Phi\left( {v_{1},v_{2}} \right)} = {\frac{1}{m - 1}{\sum\limits_{j = 1}^{m}\;{{\overset{\_}{A}\left( {v_{1},t_{j}} \right)} \cdot {\overset{\_}{A}\left( {v_{2},t_{j}} \right)}}}}} & (3) \\{{\Psi\left( {v_{1},v_{2}} \right)} = {\frac{1}{m - 1}{\sum\limits_{j = 1}^{m}\;{{\overset{\_}{A}\left( {v_{1},t_{j}} \right)} \cdot {\sum\limits_{i = 1}^{m}\;{N_{ij}{\overset{\_}{A}\left( {v_{2},t_{j}} \right)}}}}}}} & (4)\end{matrix}$

The term N_(ij) is the element of the so-called Hilbert-Nodatransformation matrix given by

$\begin{matrix}{N_{ij} = \left\{ \begin{matrix}{0\mspace{70mu}} & {{{{if}\mspace{14mu} i} = j}\mspace{25mu}} \\\frac{1}{\pi\left( {j - i} \right)} & {otherwise}\end{matrix} \right.} & (5)\end{matrix}$Synchronous spectrum Φ(v₁, v₂) represents the coordinated orsimultaneous changes of spectral intensities observed at two differentwavenumbers, v₁ and v₂, along the perturbation variable t_(k). The signof the synchronous correlation intensity becomes positive if thespectral intensities measured at the two wavenumbers mostly change inthe same direction, either increasing or decreasing. On the other hand,if one is increasing while the other is decreasing, the sign of Φ (v₁,v₂) becomes negative.

Asynchronous spectrum Ψ(v₁, v₂) represents the out-of-phase orsequential changes of spectral intensities. If Ψ(v₁, v₂)=0, thevariations of spectral intensities at two wavenumbers, v₁ and v₂ arecompletely synchronized. If the signs of Φ(v₁, v₂) and Ψ(v₁, v₂) are thesame, the overall spectral intensity variation observed at v₁predominantly occurs prior to that at v₂. If the signs are different,the order is reversed. Finally, if Φ(v₁, v₂)=0, the sequential order ofintensity variations cannot be determined. It is important to emphasizethat 2D correlation spectra only give the sequential order of spectralintensity variations but not the order of the distributed presence ofspecies responsible for the spectral signals.

Referring again to FIG. 3, in stage 370, a co-distribution correlationplot provides the perturbed regions of the protein populationdistribution (80% threshold) in solution.

Two-dimensional co-distribution spectroscopy (“2DCDS”) analysis can beused to analyze a population of protein molecules that are in solutionand how the different populations of these proteins behave. The skilledartisan's attention is called to Isao Noda, “Two-dimensionalco-distribution spectroscopy to determine the sequential order ofdistributed presence of species”, Journal of Molecular Structure, Vol.1069, pp. 54-56, which describes algorithms suitable for use in 2DCDSanalysis.

For a set of m time-dependent spectra A(v_(j), t_(k)) sequentiallyobtained during the observation interval of t₁≤t_(k)≤t_(m) with thetime-averaged spectrum Ā(v_(j)) given by Eq. (2), the characteristic(time) index is defined as

$\begin{matrix}{{\overset{\_}{k}\left( v_{j} \right)} = {{\frac{1}{m{\overset{\_}{A}\left( v_{j} \right)}}{\sum\limits_{k = 1}^{m}\;{k \cdot {A\left( {v_{j},t_{k}} \right)}}}} = {{\frac{1}{m{\overset{\_}{A}\left( v_{j} \right)}}{\sum\limits_{k = 1}^{m}\;{k \cdot {\overset{\sim}{A}\left( {v_{j},t_{k}} \right)}}}} + \frac{m + 1}{2}}}} & (6)\end{matrix}$

Dynamic spectrum Ā(v_(j), t_(k)) used here is the same as that definedin Eq. (1). The corresponding characteristic time of the distribution ofspectral intensity observed at wavenumber v_(j) is given by

$\begin{matrix}{{\overset{\_}{t}\left( v_{j} \right)} = {{\left( {t_{m} - t_{1}} \right)\frac{{\overset{\_}{k}\left( v_{j} \right)} - 1}{m - 1}} + t_{1}}} & (7)\end{matrix}$

Once again, it is understood that time used here is meant to be thegeneric description of a representative variable of appliedperturbation, so that it could be replaced with any other appropriatephysical variables, such as temperature, concentration, and pressure,selected specific to the experimental condition. The characteristic timet(v_(j)) is the first moment (about the origin of time axis, i.e., t=0)of the distribution density of the spectral intensity A(v_(j), t_(k))along the time axis bound by the observation interval between t₁ andt_(m). It corresponds to the position of the center of gravity forobserved spectral intensity distributed over the time.

Given the characteristic times, t(v₁) and t(v₂), of the timedistributions of spectral intensities measured at two differentwave-numbers, v₁ and v₂, the synchronous and asynchronousco-distribution spectra are defined as

$\begin{matrix}{{\Gamma\left( {v_{1},v_{2}} \right)} = {\sqrt{1 - \left( \frac{{\overset{\_}{t}\left( v_{2} \right)} - {\overset{\_}{t}\left( v_{1} \right)}}{t_{m} - t_{1}} \right)^{2}}{T\left( {v_{1},v_{2}} \right)}}} & (8) \\{{\Delta\left( {v_{1},v_{2}} \right)} = {\frac{{\overset{\_}{t}\left( v_{2} \right)} - {\overset{\_}{t}\left( v_{1} \right)}}{t_{m} - t_{1}}{T\left( {v_{1},v_{2}} \right)}}} & (9)\end{matrix}$where T(v₁, v₂) is the total joint variance given byT(v ₁ ,v ₂)=√{square root over (Φ(v ₁ ,v ₁)·Φ(v ₂ ,v ₂))}  (10)

Synchronous co-distribution intensity Γ(v₁, v₂) is a measure of theco-existence or overlap of distributions of two separate spectralintensities along the time axis. In contrast, asynchronousco-distribution intensity Δ(v₁, v₂) is a measure of the difference inthe distribution of two spectral signals. The term “co-distribution”denotes the comparison of two separate distributions, distinguishingthis metric from the concept of “correlation” which is based on thecomparison of two variations.

By combining Eqs. 6, 7, and 9, the expression for asynchronousco-distribution spectrum is given as

$\begin{matrix}\begin{matrix}{{\Delta\left( {v_{1},v_{2}} \right)} = {\frac{T\left( {v_{1},v_{2}} \right)}{m\left( {m - 1} \right)}{\sum\limits_{k = 1}^{m}\;{k\left\{ {\frac{A\left( {v_{2},t_{k}} \right)}{\overset{\_}{A}\left( v_{2} \right)} - \frac{A\left( {v_{1},t_{k}} \right)}{\overset{\_}{A}\left( v_{1} \right)}} \right\}}}}} \\{= {\frac{T\left( {v_{1},v_{2}} \right)}{m\left( {m - 1} \right)}{\sum\limits_{k = 1}^{m}\;{k\left\{ {\frac{\overset{\sim}{A}\left( {v_{2},t_{k}} \right)}{\overset{\_}{A}\left( v_{2} \right)} - \frac{\overset{\sim}{A}\left( {v_{1},t_{k}} \right)}{\overset{\_}{A}\left( v_{1} \right)}} \right\}}}}}\end{matrix} & (11)\end{matrix}$

The value of Δ(v₁, v₂) is set to be zero, if the condition of Ā(v₁)=0 orĀ(v₂)=0 is encountered, which indicates the lack of spectral intensitysignals at either of the wavenumber. Synchronous co-distributionspectrum can be obtained from the relationshipΓ(v ₁ ,v ₂)=√{square root over (T(v ₁ ,v ₁)²−Δ(v ₂ ,v ₂)²)}  (12)

In an asynchronous co-distribution spectrum, and for a cross peak withpositive sign, i.e., Δ(v₁, v₂)=0, the presence of spectral intensity atv₁ is distributed predominantly at the earlier stage along the time axiscompared to that for v₂. On the other hand, if Δ(v₁, v₂)<0, the order isreversed. In the case of Δ(v₁, v₂)≈0, the average distributions of thespectral intensities observed at two wavenumbers over the time courseare similar. Sign of synchronous co-distribution peaks is alwayspositive, which somewhat limits the information content of synchronousspectrum beyond the obvious qualitative measure of the degree of overlapof distribution patterns.

2DCDS is capable of providing elements of the mechanism of aggregationin a protein or any process being investigated in a weighted fashion.2DCDS can be used to directly provide the sequence of distributedpresence of species along the perturbation (e.g., time, temperature,concentration, pressure, etc.) variable axis. The technique can be usedas a complementary tool to augment 2DCOS analysis in directlyidentifying the presence of intermediate species. According to someembodiments, perturbation-dependent spectra are sequentially obtainedduring an observation interval. 2D correlation spectra (synchronousspectrum and asynchronous spectrum) are derived from the spectralvariations. Synchronous co-distribution intensity is measured as thecoexistence or overlap of distributions of two separate spectralintensities along the perturbation axis. Asynchronous co-distributionintensity is measured as the difference in the distribution of twospectral signals. For a cross peak with positive sign, i.e., Δ(v₁,v₂)>0, the presence of spectral intensity at v₁ is distributedpredominantly at the earlier stage along the time axis compared to thatfor v₂. On the other hand, if Δ(v₁, v₂)<0, the order is reversed. In thecase of Δ(v₁, v₂)≈0, the average distributions of the spectralintensities observed at two wavenumbers over the time course aresimilar.

Differences between the 2DCOS analyses provide a mean averagedescription of the pathway due to the perturbation process and itseffect on the sample, while the 2DCDS analysis provides the weightedelements in a population of molecules (proteins) during the perturbationprocess. The result of 2DCOS and 2DCDS is a direct and simplifieddescription of elements that are changing in the spectral data due tothe perturbation.

According to some embodiments, for example as shown in FIG. 4, a systemfor performing data analysis can include at least the components shownfor performing functions of methods described herein. Acquired data canbe provided to one or more computing units, including processors, foranalysis. Modules can be provided to perform or manage analysis of thedata. Such modules can include a correlation analysis module, a visualmodel generator module, and/or a human interaction module. The modulesmay be in communication with one another. In some embodiments, themodules may be implemented in software (e.g., subroutines and code). Forexample, the modules may be stored in memory and/or data storage, andexecuted by a processor. In some aspects, some or all of the modules maybe implemented in hardware (e.g., an Application Specific IntegratedCircuit (ASIC), a Field Programmable Gate Array (FPGA), a ProgrammableLogic Device (PLD), a controller, a state machine, gated logic, discretehardware components, or any other suitable devices), firmware, software,and/or a combination thereof. Additional features and functions of thesemodules according to various aspects of the subject technology arefurther described in the present disclosure.

According to some embodiments, for example as shown in FIG. 5, a methodfor verifying and preparing acquired data can be performed. The type ofdata is identified and verified. Based on the verification, the data canbe converted and/or stored or rejected with an error displayed to auser.

According to some embodiments, for example as shown in FIG. 6, a methodfor analyzing acquired data can be performed. The type of data isverified for adequate signal-to-noise ratio relative to a threshold.Based on the verification, the data can be subject to analysis orsmoothing filter process before the analysis.

According to some embodiments, for example as shown in FIG. 6, the datacan be analyzed in operations that include applying a baselinecorrelation, locating peaks, calculating data windows, calculatingcorrelations, calculating co-distributions, and/or calculatingperturbation correlation.

Data manipulation can include auto recognition of regions of interest(ROI) for the discrimination of particulates and solution. The size andnumber of the particulates can be determined to ascertain populationdistribution of particulates. Data manipulation can be performed toensure compliance such as S/N ratio determination, baseline correction,determine water vapor content, and determine signal intensity of theelements of interest within the spectral region studied. Data output forstatistical analysis can be simplified using, inter alia, the Design ofExperiment approach. The intensity and spectral position of the elementsof interest can be output as comma delimited files (*.csv). Covariance,or dynamic spectral data sets can be generated based on the perturbationof the sample of interest, the output of which can be used for furtheranalysis. For example, data output can be provided in a format thatfacilitates merging with other bioanalytical results for comparabilityassessment and sourced by: perturbation type, excipient, proteintherapeutic, protein concentration, temperature, date of acquisition,and/or bioanalytical technique. This approach would allow for thestatistical analysis to be performed for all of the experiments thatwere carried-out under similar conditions. More importantly, the resultsof the DOE analysis would be a standalone document ready for finalreporting and allow for decision making.

According to some embodiments, methods and systems described herein canapply a correlation function to the covariance or the dynamic spectraldata to generate two plots (Synchronous and Asynchronous) this algorithmis termed 2D IR correlation spectroscopy. The changes (e.g., peakintensities) in the spectral data that are in-phase with one another canbe correlated as obtained in the synchronous plot. The elements thatchange in the spectral data can be determined. The overall greatestintensity change in the spectral data can be determined. The overallsmallest intensity change in the spectral data can be determined. Theminimum number of underlying spectral contribution in a broad band suchas the amide band for proteins and peptides can be determined for curvefitting analysis, which allows for the determination of secondarystructure composition. The resolution of the spectral region beingstudied can be enhanced, particularly for broad bands in the spectra.

The changes (e.g., peak intensities) in the spectral data that areout-of-phase from one another can be correlated as obtained in theasynchronous plot. The asynchronous plot also contains the order ofevents that describe in molecular detail the protein behavior. Adetailed evaluation of the plots could be performed to ascertain theorder of events. Alternatively or in combination, this process can beautomated. A joint variance function can be applied to the covariance ordynamic spectral data to generate the merged asynchronous plot which canbe interpreted directly to determine the order of events. This methodcan alternatively be used to validate the above interpretations for thedescription of the molecular behavior of a protein which is a complexdescription. Further information for the curve-fitting routine, theinput of the number position and intensity information for thecurve-fitting routine could also be an automated process yielding thesecondary structure composition of the protein and the extent of proteinaggregated species in the samples analyzed. The intensity informationfrom the 2D IR correlation plots can be used for the quantitativedetermination of oxidative products, such as deamination. For example,deamination can be detected based on side chins. Such analysis can beused for candidate drug selection or during a protein design phase. Amachine learning approach can be implemented as a long term solution tothe complexity of the attributes needed to be correlated and solved.

According to some embodiments, for example as shown in FIG. 7, analysisof acquired data can be performed in stages to provide a comprehensivesolution that is statistically valid and highly informative with regardto protein aggregation studies. According to some embodiments, theprocess illustrated in FIG. 7 can represent applications of the processillustrated in FIG. 3. The results of QCL infrared microscopy (upperleft of FIG. 7) are shown with initial and final QCL spectra at lowtemperature, 5° C. (with greater maximum value) and high temperature,90° C. (with lesser maximum value) for an H→D (hydrogen→deuterium)exchanged full-length IgG (150 KDa) is shown in the spectral region of1700-1500 cm⁻¹. Differences in the amide I′ (1700-1600 cm⁻¹, mainly dueto peptide bond carbonyl stretching modes) and side chain (1600-1500cm⁻¹ defined in Table 1) bands are observed.

TABLE 1 Amino acids as internal probes in D₂O Position Vibrational Side(cm⁻¹) mode Chain Comment 1517 ring bend Y immediate surrounding 1545 ν(COO−) E pH, salt-bridge, H-bonding, flexibility and deamination 1567 ν(COO−) D pH, salt-bridge, H-bonding, deamination and flexibility foundin β-hairpins 1589 ν_(s) (C—N) R salt-bridge, H-bonding and flexibility1609 ν_(a) (C—N) R salt-bridge, H-bonding and flexibility 1595 ring bendH pH, H-bonding 1849 SH C covalent interaction, oxidative damage, longrange flexibility

By subtracting the initial spectrum at low temperature from allsubsequent spectra, the spectral changes due to the temperature increaseare revealed (revealing the changes in the protein behavior) which arereferred to as covariance spectral data, but also commonly referred toas difference spectra. A cross correlation function is then applied tothese spectral changes to determine the relationship between the peaksobserved. Two plots are generated, the synchronous and asynchronousplots which provide the correlation between the resulting peaks observeddue to the perturbation of the protein sample. These plots provide awealth of molecular information and the sequential order of molecularevents which describe the behavior of the protein. A synchronous plot(lower left of FIG. 7) containing auto peaks (peaks on the diagonal) isshown with the aggregation peak. This diagram represents the greatestintensity change in the protein, and two additional auto-peaks withlower intensity changes are observed. The relationship between thesepeaks is determined based on observation of the cross peaks(off-diagonal peaks), which are either positive or negative and providethe relationship between the different auto peaks observed on thediagonal (i.e., the changes in intensity due to the subtraction of theinitial spectrum). In this hypothetical case, the relationship observedresults in an aggregation event that involves the helical secondarystructure of the protein, which is also validated by the presence of thetyrosine residue found in this helical motif, thus serving as aninternal probe for the aggregation process of the protein. Therefore,the tyrosine peak defines the region of the protein that is aggregating.2DCOS analysis provides valuable detailed molecular information notavailable before by other orthogonal techniques such as SEC, DSC andDLS. Results obtained from the QCL are highly reproducible and have beentested rigorously using statistics. The QCL infrared spectral region ishighly selective and sensitive thus allowing for the simultaneous studyof the protein conformational changes as well as 6 of the 20 amino acidside chain vibrational modes (see Table 1).

Example 1

A developability and comparability assessment was performed for threeantibody drug conjugate fragments (FIGS. 8A-B). The analysis involved atotal of 47 experiments. A QCL microscope was used to perform imageacquisition of 43 DOE conditions, 16 of which involved the comparison of3 ADC fragments termed ADC0, ADC1 & ADC2 in HEPES buffered solution atpH 6.6 and T=24-30° C. It was determined that ADC2 was aggregate freeunder the conditions studied, whereas ADC1 had some aggregate species,but when heated to 28° C. the aggregate returned to solution (FIG.9A-B). Moreover, ADC0 candidate had aggregate species present, but upontemperature increase the presence of aggregate species increased. Theseaggregate species were determined to be ADC0. Similar results were foundfor ADC1 using 2DCDS analysis (FIG. 10).

Also, the spectral analysis of aggregate free ADC2 was performed in thepresence of varying excipients (sucrose and NaCl) at near-roomtemperatures, T=24-26° C. (FIGS. 11A-B). The value added of determiningreproducibility of the analysis by selecting different regions ofinterest (ROI) shown as boxed within the QCL images (FIG. 11A) whichwere analyzed spectroscopically offline (FIG. 11B). The sucroseexcipient is shown at 1420-1520 cm⁻¹. Also shown are the amide I′ andside chain bands (1520-1700 cm⁻¹), thus proving the high sensitivity andselectivity of the technique. Further evidence is shown in FIGS. 12A-C.Analytically, the capability of detecting directly both the excipientand the protein therapeutic is of high value to the biopharma industry,because it allows for validation of the presence of the excipient ineach formulation. The HT-DCA Platform would provide both the accuracyand reproducibility required for the statistical analysis as well as thehighly valued molecular information of the constituents within thesample.

A full factorial design of 516 spectra and Normal Distribution Analysiswas performed for 43 experiments using the QCL Microscope (QCL) undervarying conditions. The QbD experimental setup was such that 324spectral data were analyzed representing the evaluation of ADC2 in thepresence of varying amounts of NaCl, sucrose and varying ratios of bothexcipients (i.e., NaCl and sucrose). The sample size was determined tobe n=8-12 depending on the standard deviation. Developability andcomparability assessment was pursued with ADC2 below are the summary ofthe results obtained at 15, 30 and 60% Sucrose at 26° and 28° C. Similarresults were obtained for varying concentration (325, 350 and 400 mM) ofNaCl and varying ratios of sucrose and NaCl as excipients. Typically,the results obtained converged with p values greater than 0.8 (FIG. 13).The distribution analysis was followed by a DOE statistical evaluationusing a stepwise all model fit, concluding with the AIC & BIC models(FIG. 14, 15) which reached the same outcome that is 18.5% sucrose asthe best excipient for ADC2.

The QCL spectral analysis capabilities of a HT-DCA platform providefurther molecular analysis and stability determination of the proteintherapeutic. This type of analysis is highly informative, allowing forthe optimum design of the protein therapeutic candidate. Two types ofcorrelation analysis were performed: 2DCOS analysis and 2DCDS analysis,providing information regarding the behavior of the protein therapeuticin solution.

Conceptual analysis of the 2D IR correlational plots was applied toinfrared spectra of proteins. The amide I′ and side chain bands arebroad and comprised of many underlying contributions, whether they areconformationally sensitive as are the carbonyl stretches within thepeptide bonds or side chain vibrational modes which are informative oftheir neighboring environment and weak interactions. To extract thisinformation, covariance spectra are generated by subtracting thereference spectrum from all subsequent spectra. For example, in aprotein thermal denaturation study (temperature perturbation), theinitial spectrum at low temperature would be used for subtraction. Thecovariance spectra generated include the changes in intensity due to thetemperature increase. A correlation function is then applied to the dataset which will relate the changes in intensity observed in thecovariance spectra in the form of 2 separate graphs with increasedresolution. These plots are capable of resolving highly overlappedbands, establishing the most flexible regions of a protein, decipheringthe aggregation mechanism in a protein and establishing protein-targetinteractions. 2D IR correlational plots are termed synchronous andasynchronous plots. These plots are symmetrical in nature and forinterpretation purposes, reference is made to the top half of each plot.The synchronous plot has positive peaks on the diagonal known as theauto-peaks. Auto-peaks contain the overall changes in intensity observedfor the entire spectral data set. The magnitude of the change can beidentified and used to determine the flexibility or susceptibility aregion of the protein may have due to the perturbation. The position andnumber of these peaks is used to determine the underlying spectralcontributions for the amide I′ and side chain bands (see Table 2).

TABLE 2 Summary of the band assignments for ADC2 in HEPES buffersolution with 15% sucrose distance Wavenumber number line (cm) (cm⁻¹)Band Assignment of residues protein backbone a′ 1.0 1682.6 β-turn a 1.31670.3 β-turn (hinge loop) b 2.1 1652.8 random coil c 2.5 1632.0 β-sheet(antiparallel) d 2.8 1626.4 β-strand side chains e 3.7 1609.7 Arg(ν_(as) (CN₃H₅ ⁺) 3 f 4.3 1590.1 His (C═C) 9 g 4.9 1580.4 Arg (v_(s)(CN₃H₅ ⁺) 3 h 6.0 1553.6 Asp⁻ (ν_(as) (COO⁻) 10 i 6.4 1543.8 Glu⁻(ν_(as) (COO⁻) 8 j 7.0 1529.2 COO (C-term) 1 k 7.5 1517.0 Tyr (C═C) 5

The synchronous plot, also has off diagonal peaks known as the crosspeaks. These cross peaks determine the relationship of the auto-peaks.The cross peaks observed in the synchronous plot are due to changes inintensity that are in-phase with one another. One can consider 2 peakswhose intensity changed incrementally or vice versa, these twoauto-peaks would have an accompanying cross peak that represents theirmutual relationship (FIGS. 16A-B).

The asynchronous plot does not contain peaks on the diagonal, yetrenders enhanced spectral resolution. The resulting cross peaks are dueto peaks whose intensity in the covariance spectra changed out-of-phasefrom one another and consequently provides detailed information. Amongthem, are the sequential order of molecular events due to the thermalperturbation. The cross peaks in the asynchronous plot are eitherpositive or negative and one can determine the sequential order. Ingeneral, if the sign of the cross peaks are positive in both plots, theorder defined in the asynchronous plot is retained. Therefore, apositive cross peak means v₁ occurs prior to v₂. This interpretation isdesignated as true if and only if the same cross peak in the synchronousplot is also positive. However, when the sign of the cross peaks aredifferent in both plots, then the order is reversed.

Applying this to the plots of FIGS. 16A-B, a cross peak in theasynchronous plot is found to be positive at (1652, 1632). The 1652 cm⁻¹(v₁) peak is perturbed prior to 1632 cm⁻¹ (v₂). The molecularinterpretation would be that the π-helix is perturbed prior to theanti-parallel β-sheets within the protein (Table 2). Similarly, theβ-turns (hinge loops, 1670.3 cm⁻¹) are perturbed prior to theanti-parallel β-sheets. Furthermore, these plots were used to determinehow the sucrose stabilized ADC2 in solution. Hydrogen bonding betweenside chains and the sucrose stabilized the β-turns (hinge loops) andthus also stabilized the β-sheets. More importantly, the molecularchanges that occurred in the protein fragment of interest are shown inFIG. 17.

Although the temperature perturbation was limited to near roomtemperature, the analysis still allowed for the determination of theH-bonding interaction between the side chains and its aqueousenvironment and the excipient (sucrose). Also, these interactionsstabilized the secondary structure of ADC2.

The 2DCDS analysis was found to be useful for the evaluation of thedynamics of a protein solution and the distribution of conformationaldynamics within a temperature range, in the current case the temperaturerange was small only 26-28° C. for ADC2 in HEPES buffers and in thepresence of 15% sucrose (FIGS. 18A-B). The interpretation of theasynchronous co-distribution plot is straight forward when compared tothe 2D IR correlation. No comparison of cross peak signs between theplots is required. For a positive cross peak, it can be determined thatv₁ occurs prior to v₂. Moreover, for the negative cross peak, it can bedetermined that v₂ occurs prior to v₁.

No aggregation was observed for this protein. With reference to theasynchronous plot (FIG. 18B) an inter-dependence is observed between theβ-turns also referred to as hinge loops (1660 cm⁻¹) and the negativelycharged aspartate (1553 cm⁻¹), and glutamate (1543 cm⁻¹) residues forthis protein in solution. This result is consistent with their locationwithin the β-turns motifs of ADC2. 2DCOS analysis and 2DCDS analysisallowed for the complete description of ADC2 and the stabilizing effectof sucrose on ADC2 at the molecular level (FIGS. 16A-18B). In summary,the main stabilizing feature in ADC2 was that of the hinge loops by thesalt-bridge interactions observed between the arginines and the nearbyaspartate residues. The disruption of salt-bridge interactions wereprevented by the second disulfide bridge introduced by site directedmutagenesis. Further stabilization was achieved by formulationconditions which included sucrose as excipient. Specifically, 15%sucrose also provided stabilization by H-bonding with these sameresidues.

TABLE 3 Summary of the curve-fit results stating the secondary structurecomposition of ADC fragment 2 at 26° C. Contributing Sub-bands SecondaryStructure position Composition spectrum # (cm⁻¹) Area assignment (%)Comments 12 1688.2 4.1 β-turn 1670.6 12.5 β-turn (hinge loop) 29 sum ofβ-turns 1639.4 18.8 β-sheet (anti) 32.8 total area was 57.3 1623.7 9.9β-strand 17.3 essentially β-structure 1655.2 11.9 random coil 20.779.10% 13 1691.1 3.27 β-turn 1670.2 13.82 β-turn (hinge loop) 29.4 sumof β-turns 1639.4 19.3 β-sheet (anti) 33.2 total area was 58.1 1624.010.2 β-strand 17.5 essentially β-structure 1655.2 11.54 random coil 19.880.10% 14 1692.2 1.86 β-turn 1672.2 16.0 β-turn (hinge loop) 29.3 sum ofβ-turns 1639.9 21.9 β-sheet (anti) 35.9 total area was 60.8 1625.1 10.4β-strand 17.0 essentially β-structure 1656.1 10.7 random coil 17.6 82.0%

FIG. 19 shows plots corresponding to the results shown in Table 3.

Example 2

Samples including the National Institute of Standards & TechnologyReference Material 8671 (RM8671) Lot No. 14HB-D-002, a humanized IgG1κmonoclonal antibody (NIST mAb), in H₂O were studied for analysisaccording to methods described herein. Samples were added to cells of aCaF₂ slide for data acquisition using a QCL microscope. The appliedperturbation was temperature within the range of 24-60° C. with 4° C.temperature intervals. QCL IR spectral data was acquired using a 4×magnitude objective at 4 cm⁻¹ with data encoded every 0.5 cm⁻¹ andbaseline corrected.

The NIST mAb standard is an IgG1κ protein. The amino acid sequences ofthe heavy chain (SEQ ID NO:5) and the light chain (SEQ ID NO:6) of theantibody are presented below.

RM 8671 Heavy Chain AAQVTLRESGPALVKPTQTLTLTCTFSGFSLSTAGMSVGWIRQPPGKALEWLADIWWDDKKHYNPSLKDRLTISKDTSKNQVVLKVTNMDPADTATYYCARDMIFNFYFDVWGQGTTVTVSS ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGQTQTYICNVNHKPSNTKVDKRV EPKSCDKTHTCPPCP APELLGGSPVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSL SPGKRM 8671 Light Chain DIQMTQSPSTLSASVGDRVTITCSASSRVGYMHWYQQKPGKAPKLLIYDTSKLASGVPSRFSGSGSGTEFTLTISSLQPDDFATYYCFQGSGYPFTFGGGTKVEIK RTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQG LSSPVTKSFNRGEC

Assignment of amino acid side chains for the sample is provided inTables 4 and 5.

TABLE 4 Assignment of heavy amino acid side chains for NIST mAb in H₂Onumber of side chain position residues in item Heavy Chain codevibrational mode (cm⁻¹) sequence 1 Tyr Y ν (C═C) 1518 32 2 Glu⁻ E ν(COO−) 1543-1560 40 3 Asp⁻ D ν (COO−) 1570-1574 42 4 His H ν (C═C) 159620 5 C-term end ν (COO−) 1598 2 6 Arg R ν_(as) (CN₃H₅ ⁺) 1673 22 7 Arg Rν_(s) (CN₃H₅ ⁺) 1633 22 8 Lys K δ_(as) (NH₃ ⁺) 1629 70 9 Lys K δ_(s)(NH₃ ⁺) 1526 70 10 Asn N ν (C═O) 1678 36 11 Gln Q ν (C═O) 1670 32

TABLE 5 Assignment of light amino acid side chains for NIST mAb in H₂Onumber of side chain position residues in item light Chain codevibrational mode (cm⁻¹) sequence 1 Tyr Y ν (C═C) 1518 20 2 Glu⁻ E ν(COO−) 1543-1560 18 3 Asp⁻ D ν (COO−) 1570-1574 20 4 His H ν (C═C) 15966 5 C-term end ν (COO−) 1598 2 6 Arg R ν_(as) (CN₃H₅ ⁺) 1673 12 7 Arg Rν_(s) (CN₃H₅ ⁺) 1633 22 8 Lys K δ_(as) (NH₃ ⁺) 1629 28 9 Lys K δ_(s)(NH₃ ⁺) 1526 28 10 Asn N ν (C═O) 1678 10 11 Gln Q ν (C═O) 1670 24

As shown in FIG. 20A, QCL spectra of NIST mAb at 50 mg/mL in the MID IRspectral region of 1750-1400 cm⁻¹ was acquired within the temperaturerange of 24-60° C. in H₂O. FIG. 20A shows overlaid spectra showing theamide I, II and III bands. Based on the spectral data synchronous (FIG.20B) and asynchronous (FIG. 20C) 2D IR correlation analysis plots weregenerated. Overlapping H₂O absorbance was observed in the amide I bandnot so in the amide II and III bands, suggesting sufficient proteinconcentration was achieved for analysis. The method applied, accordingto embodiments of the present disclosure, eliminates the need for thesubjective manipulation of H₂O or reference subtraction by the user.

As shown in FIG. 21A, QCL spectra of NIST mAb at 50 mg/mL in the MID IRspectral region of 1750-1500 cm⁻¹ was acquired within the temperaturerange of 24-60° C. in H₂O. FIG. 21A shows overlaid spectra showing boththe amide II and III bands. Based on the spectral data synchronous (FIG.21B) and asynchronous (FIG. 21C) plots. The correlation between theamide I and II bands is established. Enhanced resolution is achievedthrough the use of the asynchronous plot.

Peak assignments of NIST mAb at 50 mg/mL in H₂O are provided in Table 6.

TABLE 6 Summary of peak assignments of NIST mAb at 50 mg/mL in H₂O PeakAssignment Peak Position (cm⁻¹) β-turn 1692 β-turn 1681.6 Arg 1668 HingeLoop 1660 α-helix 1652 β-sheet 1635 Agg 1618 His 1602 Asp⁻ 1573 Glu⁻1542 Try 1515.8 Note: Aggregation (Agg)

The sequential order of events for NIST mAb at 50 mg/mL in H₂O underthermal stress within the temperature range of 24-60° C. is shown inFIG. 22. The 1635.5 cm⁻¹ is assigned antiparallel β-sheet due to theperturbation of the 1692 cm⁻¹ β-turn, both vibrational modes are themost stable. Also, 1618 cm⁻¹ has been assigned to protein Aggregationwhich was thermally induced at 60° C. based on this work. 1652 cm⁻¹ maybe assigned to α-helix.

The sequential order of events for the NIST mAb at 50 mg/mL in H₂O isprovided in Table 7.

TABLE 7 Summary of sequential order of events for NIST mAb at 50 mg/mLin H₂O Event Asynchronous and Synchronous plot analysis 1 β-turn (1681.6cm⁻¹) → Arg (1668 cm⁻¹) 2 Asp⁻ (1573 cm⁻¹), Glu⁻ (1542 cm⁻¹), Try(1515.8 cm⁻¹) → α- helix (1652 cm⁻¹) 3 Arg (1668 cm⁻¹) → α-helix (1652cm⁻¹) 4 Hinge loop (1660 cm⁻¹) → His (1602 cm⁻¹) 5 β-turn (1681.6 cm⁻¹)→ His (1602 cm⁻¹) 6 Hinge loop (1660 cm⁻¹) → Agg (1618 cm⁻¹) 7 α-helix(1652 cm⁻¹) → Agg (1618 cm⁻¹) 8 Hinge loop (1660 cm⁻¹) → α-helix (1652cm⁻¹) 9 His (1602 cm⁻¹) → β-turn (1692 cm⁻¹) 10 β-sheet (1635 cm⁻¹) →β-turn (1692 cm⁻¹) Note: Aggregation (Agg) β-sheet and β-turn appear ascoupled modes indicating presence of antiparallel β-sheet

FIG. 23 shows an asynchronous 2D IR co-distribution analysis plot forNIST mAb at 50 mg/mL in H₂O under thermal stress within the temperaturerange of 24-60° C. The thermal stress within the NIST mAb (50 mg/mL) inthe temperature range of 24-60° C. and spectral region 1760-1380 cm⁻¹.This plot provides the most common response in a population of proteinsin solution. Therefore in the case of the NIST mAb at 50 mg/mL, itsthermal stress was related to the perturbation of the glutamates alongwith the Arg presumably through salt-bridge interaction. GlutamatesH-bonded to His residues, and these residues are located within theα-helices and β-sheets.

FIGS. 24A-D show an example of automated analysis providing therelationship within the (A) overlaid raw spectral data, 2D IRcorrelation: (B) synchronous and (C) asynchronous plots, and (D)co-distribution asynchronous plot. Broken vertical lines are providedduring automated analysis based on the auto peak (positive peaks on thediagonal shown in FIG. 24B) absolute intensity values within thesynchronous plot.

Example 3

Samples including Bovine Serum Albumin (“BSA”) in H₂O were studied foranalysis according to methods described herein. Samples were added tocells of a CaF₂ slide for data acquisition using a QCL microscope. Theapplied perturbation was temperature within the range of 24-60° C. with4° C. temperature intervals. QCL spectral data was acquired using a 4×magnitude objective at 4 cm⁻¹ with data encoded every 0.5 cm⁻¹ andbaseline corrected.

(SEQ ID NO: 7) DTHKSEIAHRFKDLGEEHFKGLVLIAFSQYLQQCPFDEHVKLVNELTEFAKTCVADESHAGCEKSLHTLFGDELCKVASLRETYGDMADCCEKQEPERNECFLSHKDDSPDLPKLKPDPNTLCDEFKADEKKFWGKYLYEIARRHPYFYAPELLYYANKYNGVFQECCQAEDKGACLLPKIETMREKVLTSSARQRLRCASIQKFGERALKAWSVARLSQKFPKAEFVEVTKLVTDLTKVHKECCHGDLLECADDRADLAKYICDNQDTISSKLKECCDKPLLEKSHCIAEVEKDAIPENLPPLTADFAEDKDVCKNYQEAKDAFLGSFLYEYSRRHPEYAVSVLLRLAKEYEATLEECCAKDDPHACYSTVFDKLKHLVDEPQNLIKQNCDQFEKLGEYGFQNALIVRYTRKVPQVSTPTLVEVSRSLGKVGTRCCTKPESERMPCTEDYLSLILNRLCVLHEKTPVSEKVTKCCTESLVNRRPCFSALTPDETYVPKAFDEKLFTFHADICTLPDTEKQIKKQTALVELLKHKPKATEEQLKTVMENFVAFVDKCCAADDKEACFAVEGPKLVVSTQTALA

Assignment of amino acid side chains for the sample is provided in Table8.

TABLE 8 Assignment of amino acid side chains for BSA in H₂O number ofposition residues in item side chain code vibrational mode (cm⁻¹)sequence 1 Tyr Y ν (C═C) 1518 20 2 Glu⁻ E ν (COO−) 1543-1560 62 3 Asp⁻ Dν (COO−) 1570-1574 39 4 His H ν (C═C) 1596 17 5 C-term end ν (COO−) 15981 6 Arg R ν_(as) (CN₃H₅ ⁺) 1673 21 7 Arg R ν_(s) (CN₃H₅ ⁺) 1633 21 8 LysK δ_(as) (NH₃ ⁺) 1629 48 9 Lys K δ_(s) (NH₃ ⁺) 1526 48 10 Asn N ν (C═O)1678 14 11 Gln Q ν (C═O) 1670 21

As shown in FIG. 25A, QCL spectra of BSA at 40 mg/mL in the MID IRspectral region of 1750-1500 cm⁻¹ was acquired within the temperaturerange of 24-60° C. in H₂O. FIG. 25A shows overlaid spectra showing theamide I and II bands. Based on the spectral data synchronous (FIG. 25B)and asynchronous (FIG. 25C) 2D IR correlation analysis plots weregenerated. The correlation between the amide I and II bands isestablished. Enhanced resolution is achieved through the use of theasynchronous plot. Also, the highest intensity auto peak within thesynchronous plot is due to helical perturbation for this globularprotein. In addition, no aggregation was observed.

Peak assignments of BSA at 40 mg/mL are provided in Table 9.

TABLE 9 Summary of peak assignments of BSA at 40 mg/mL Peak AssignmentPeak Position (cm⁻¹) β-turn 1698 β-turn 1684 Arg 1672.4 α-helix 1653.9β-sheet/Arg 1629.6 His 1606.5 Asp⁻ 1584.5 Asp⁻ 1576.4 Asp⁻ 1567.1 Glu⁻1559 Glu⁻ 1541.7 Lys 1530 Lys 1525.5 Tyr 1518.5

The sequential order of events for BSA at 40 mg/mL under thermal stresswithin the temperature range of 24-60° C. is shown in FIG. 26. Thesequential order of events for the BSA at 40 mg/mL is also provided inTable 10.

TABLE 10 Summary of sequential order of events for BSA at 40 mg/mL EventAsynchronous and Synchronous plot analysis 1 Asp⁻ (1567 cm⁻¹) → Asp⁻(1584 cm⁻¹) 2 Lys (1530 cm⁻¹), Lys (1525.5 cm⁻¹) → β-sheet/Arg (1629.5cm⁻¹) 3 Glu⁻ (1541.7 cm⁻¹) → α-helix (1653.9 cm⁻¹) 4 Asp⁻ (1584 cm⁻¹) →Glu⁻ (1541.7 cm⁻¹) 5 β-sheet/Arg (1629 cm⁻¹) → His (1606.5 cm⁻¹) 6 Tyr(1518.5 cm⁻¹) → His (1606.5 cm⁻¹) 7 α-helix (1652 cm⁻¹) → Asp⁻ (1576.4cm⁻¹) 8 Arg (1672.4 cm⁻¹) → Glu⁻ (1559 cm⁻¹) 9 His (1606.5 cm⁻¹) →β-turn (1684 cm⁻¹) 10 Glu⁻ (1559 cm) → Asp⁻ (1576.4 cm) 11 β-turn (1698cm⁻¹) → β-turn (1684 cm⁻¹)

The aspartates (1567 cm⁻¹) and glutamates (1584 cm⁻¹) located within thehelical regions (1653.9 cm⁻¹) that are involved in salt bridgeinteractions with lysines (1530.0 and 1525.5 cm⁻¹) are perturbed first;followed by the β-sheets (1629.6 cm⁻¹), then the tyrosines (1518 cm⁻¹)and histidines (1606.5 cm⁻¹) within the antiparallel β-sheets (1629.6cm⁻¹) β-turns (1698 cm⁻¹) are perturbed. Finally at high temperature thesalt bridge interactions involving arginines with glutamates (1560 cm⁻¹)and aspartates (1576.4 cm⁻¹) located close to β-turns (1684.0 cm⁻¹) areperturbed.

FIG. 27 shows an asynchronous 2D IR co-distribution analysis plot forBSA 40 mg/mL in H₂O under thermal stress within the temperature range of24-60° C. and spectral region of 1750-1380 cm⁻¹. In the case of the BSA40 mg/mL, its thermal stress was related to the perturbation of theglutamates within the n-turns and the helical regions.

Example 4

Samples including a mixture of NIST mAb and BSA in H₂O were studied foranalysis according to methods described herein. Samples were added tocells of a CaF₂ slide for data acquisition using a QCL microscope. Theapplied perturbation was temperature within the range of 24-60° C. with4° C. temperature intervals. QCL spectral data was acquired using a 4×magnitude objective at 4 cm⁻¹ with data encoded every 0.5 cm⁻¹ andbaseline corrected.

As shown in FIG. 28A, QCL spectra of NIST mAb/BSA (1:2, mol ratio)mixture in the spectral region of 1750-1500 cm⁻¹ was acquired within thetemperature range of 24-60° C. in H₂O. FIG. 28A shows overlaid spectrashowing the amide I and II bands. Based on the spectral data synchronous(FIG. 28B) and asynchronous (FIG. 28C) 2D IR correlation analysis plotswere generated. Overall the synchronous plot contour exhibited featuresthat are distinguishable both for NIST mAb and that of BSA purecomponents.

Peak assignments of NIST mAb/BSA are provided in Table 11.

TABLE 11 Summary of peak assignments of NIST mAb/BSA Protein PeakAssignment Peak Position (cm⁻¹) NIST mAb β-turn 1692 NIST mAb β-turn1681.6 NIST mAb Arg 1668 BSA α-helix 1653.9 NIST mAb α-helix 1652 NISTmAb β-sheet 1635 BSA β-sheet/Arg 1629.6 NIST mAb Agg 1618 BSA His 1606.5NIST mAb Asp⁻ 1573 BSA Asp⁻ 1567.1 BSA Glu⁻ 1559 NIST mAb Glu⁻ 1542 BSAGlu⁻ 1541.7 BSA Lys 1525.5 Note: Aggregation (Agg)

Example 5

Samples including Lysozyme in H₂O were studied for analysis according tomethods described herein. Custom CaF₂ slide cells were used with 7 μmpath-length for samples in H₂O. The applied perturbation was temperaturewithin the range of 24-60° C. with 4° C. temperature intervals. QCL IRspectral data was acquired using a 4× magnitude objective at 4 cm⁻¹ withdata encoded every 0.5 cm⁻¹ and baseline corrected.

Below is an amino acid sequence for the Lysozyme analyzed.

(SEQ ID NO: 8) KVFGRCELAAAMKRHGLDNYRGYSLGNWVCAAKFESNFNTQATNRNTDGSTDYGILQINSRWWCNDGRTPGSRNLCNIPCSALLSSDITASVNCAKKIVSDGNGMNAWVAWRNRCKGTDVQAWIRGCRL

Assignment of amino acid side chains for the sample is provided in Table12.

TABLE 12 Assignment of amino acid side chains for Lysozyme in H₂O numberof position residues in item side chain code vibrational mode (cm⁻¹)sequence 1 Tyr Y ν (C═C) 1518 3 2 Glu⁻ E ν (COO−) 1543-1560 5 3 Asp⁻ D ν(COO−) 1570-1574 7 4 His H ν (C═C) 1596 1 5 C-term end ν (COO−) 1598 1 6Arg R ν_(as) (CN₃H₅ ⁺) 1673 11 7 Arg R ν_(s) (CN₃H₅ ⁺) 1633 11 8 Lys Kδ_(as) (NH₃ ⁺) 1629 6 9 Lys K δ_(s) (NH₃ ⁺) 1526 6 10 Asn N ν (C═O) 167815 11 Gln Q ν (C═O) 1670 4

As shown in FIG. 29A, QCL spectra of Lysozyme at 600 mg/mL in thespectral region of 1750-1500 cm⁻¹ was acquired within the temperaturerange of 24-60° C. in H₂O. FIG. 29A shows overlaid spectra showing theamide I and II bands. Based on the spectral data synchronous (FIG. 29B)and asynchronous (FIG. 29C) 2D IR correlation analysis plots weregenerated. Correlation between the helical regions of the protein andthe n-turns can be established due to the thermal stress. Also, the weakinteractions between glutamate, aspartate and arginine, lysine,histidine residues are critical to the stability of Lysozyme asestablished by the correlations observed in both the synchronous andasynchronous plot. No aggregation was observed for this protein.

Peak assignments of Lysozyme at 600 mg/mL are provided in Table 13.

TABLE 13 Summary of peak assignments of Lysozyme at 600 mg/mL PeakAssignment Peak Position (cm⁻¹) β-turn 1698 β-turn 1683.8 Arg 1672.4Arg/Asn/Gln 1666.6 Hinge loop 1660.5 α-helix 1647 β-sheet 1637.2 Arg1628.7 His 1596.6 Asp⁻ 1572.3 Asp⁻ 1566.1 Glu⁻ 1556.3 Glu⁻ 1547.8 Glu⁻1536.8 Lys 1526.9 Tyr 1514.6

The sequential order of events for Lysozyme at 600 mg/mL under thermalstress within the temperature range of 24-60° C. is shown in FIG. 30.The sequential order of events for the BSA at 40 mg/mL is also providedin Table 14.

TABLE 14 Summary of sequential order of events for Lysozyme at 600 mg/mLEvent Asynchronous and Synchronous plot analysis 1 Tyr (1514.6 cm⁻¹) →Lys (1526.9 cm⁻¹) 2 Lys (1526.9 cm⁻¹)→ β-sheet (1637.2 cm⁻¹) 3 Lys(1526.9 cm⁻¹) → Arg (1628.7 cm⁻¹) 4 Arg (1628.7 cm⁻¹) → Glu⁻ (1536.8cm⁻¹) 5 β-sheet (1637.2 cm⁻¹) → Glu⁻ (1556.3 cm⁻¹) 6 Glu⁻ (1536.8 cm⁻¹)→ Glu⁻ (1556.3 cm⁻¹) 7 Glu⁻ (1556.3 cm⁻¹) → Glu⁻ (1547.8 cm⁻¹) 8 α-helix(1647 cm⁻¹) → β-turn (1683 cm⁻¹) 9 β-turn (1698 cm⁻¹) → Arg/Asn/Gln(1666.6 cm⁻¹) 10 Glu⁻ (1547.8 cm⁻¹) → Asp⁻ (1566.1 cm⁻¹, 1572.3 cm⁻¹) 11Glu⁻ (1547.8 cm⁻¹) → Hinge loop (1660.5 cm⁻¹) 12 Glu⁻ (1556.3 cm⁻¹) →α-helix (1647 cm⁻¹) 13 Hinge loop (1660.5 cm⁻¹) → His (1596.6 cm⁻¹) 14Tyr (1514.6 cm⁻¹) → Arg/Asn/Gln (1666.6 cm⁻¹)

The tyrosines (1514.6 cm⁻¹) and lysines (1526.9 cm⁻¹) are perturbedfirst, followed by the arginines (1628.7 cm⁻¹) then the β-sheets (1637.2cm⁻¹), then the glutamates (1536.8 cm⁻¹) within the β-sheets followed bythe glutamates (1556 cm⁻¹) located within the helical regions (1647.0cm⁻¹) and the β-turns (1698.0 cm⁻¹ and 1683.8 cm⁻¹) followed byglutamates (1547.8 cm⁻¹) the hinge loops (1660.5 cm⁻¹) then theaspartates (1566.1,1672.3 cm⁻¹) and a single histidine (1596.6 cm⁻¹)presumably interacting with an aspartate by H-bonding interactionlocated near the N-terminal end and finally the Arg, Asn, Gln allassigned to (1666.6 cm⁻¹). No aggregation was observed.

FIG. 31 shows an asynchronous 2D IR co-distribution analysis plot forLysozyme at 600 mg/mL in H₂O under thermal stress within the temperaturerange of 24-60° C. and spectral region of 1750-1500 cm⁻¹. In the case ofthe Lysozyme (600 mg/mL), its thermal stress was related to theperturbation of the, tyrosines located within the hinge loops andlysines and glutamates located near or at the β-turns and helicalregions.

FIG. 32 is a block diagram illustrating an exemplary computer systemwith which a computing device (e.g., of FIG. 4) can be implemented. Incertain embodiments, the computer system 1900 may be implemented usinghardware or a combination of software and hardware, either in adedicated server, or integrated into another entity, or distributedacross multiple entities.

The computer system 1900 includes a bus 1908 or other communicationmechanism for communicating information, and a processor 1902 coupledwith the bus 1908 for processing information. By way of example, thecomputer system 1900 may be implemented with one or more processors1902. The processor 1902 may be a general-purpose microprocessor, amicrocontroller, a Digital Signal Processor (DSP), an ApplicationSpecific Integrated Circuit (ASIC), a Field Programmable Gate Array(FPGA), a Programmable Logic Device (PLD), a controller, a statemachine, gated logic, discrete hardware components, and/or any othersuitable entity that can perform calculations or other manipulations ofinformation.

The computer system 1900 can include, in addition to hardware, code thatcreates an execution environment for the computer program in question,e.g., code that constitutes processor firmware, a protocol stack, adatabase management system, an operating system, or a combination of oneor more of them stored in an included memory 1904, such as a RandomAccess Memory (RAM), a flash memory, a Read Only Memory (ROM), aProgrammable Read-Only Memory (PROM), an Erasable PROM (EPROM),registers, a hard disk, a removable disk, a CD-ROM, a DVD, and/or anyother suitable storage device, coupled to the bus 1908 for storinginformation and instructions to be executed by the processor 1902. Theprocessor 1902 and the memory 1904 can be supplemented by, orincorporated in, special purpose logic circuitry.

The instructions may be stored in the memory 1904 and implemented in oneor more computer program products, i.e., one or more modules of computerprogram instructions encoded on a computer readable medium for executionby, or to control the operation of, the computer system 1900, andaccording to any method well known to those of skill in the art,including, but not limited to, computer languages such as data-orientedlanguages (e.g., SQL, dBase), system languages (e.g., C, Objective-C,C++, Assembly), architectural languages (e.g., Java, .NET), and/orapplication languages (e.g., PHP, Ruby, Perl, Python). Instructions mayalso be implemented in computer languages such as array languages,aspect-oriented languages, assembly languages, authoring languages,command line interface languages, compiled languages, concurrentlanguages, curly-bracket languages, dataflow languages, data-structuredlanguages, declarative languages, esoteric languages, extensionlanguages, fourth-generation languages, functional languages,interactive mode languages, interpreted languages, iterative languages,list-based languages, little languages, logic-based languages, machinelanguages, macro languages, metaprogramming languages, multiparadigmlanguages, numerical analysis, non-English-based languages,object-oriented class-based languages, object-oriented prototype-basedlanguages, off-side rule languages, procedural languages, reflectivelanguages, rule-based languages, scripting languages, stack-basedlanguages, synchronous languages, syntax handling languages, visuallanguages, wirth languages, and/or xml-based languages. The memory 1904may also be used for storing temporary variable or other intermediateinformation during execution of instructions to be executed by theprocessor 1902.

A computer program as discussed herein does not necessarily correspondto a file in a file system. A program can be stored in a portion of afile that holds other programs or data (e.g., one or more scripts storedin a markup language document), in a single file dedicated to theprogram in question, or in multiple coordinated files (e.g., files thatstore one or more modules, subprograms, or portions of code). A computerprogram can be deployed to be executed on one computer or on multiplecomputers that are located at one site or distributed across multiplesites and interconnected by a communication network. The processes andlogic flows described in this specification can be performed by one ormore programmable processors executing one or more computer programs toperform functions by operating on input data and generating output.

The computer system 1900 further includes a data storage device 1906such as a magnetic disk or optical disk, coupled to the bus 1908 forstoring information and instructions. The computer system 1900 may becoupled via an input/output module 1910 to various devices (e.g.,devices 1914 and 1916). The input/output module 1910 can be anyinput/output module. Exemplary input/output modules 1910 include dataports (e.g., USB ports), audio ports, and/or video ports. In someembodiments, the input/output module 1910 includes a communicationsmodule. Exemplary communications modules include networking interfacecards, such as Ethernet cards, modems, and routers. In certain aspects,the input/output module 1910 is configured to connect to a plurality ofdevices, such as an input device 1914 and/or an output device 1916.Exemplary input devices 1914 include a keyboard and/or a pointing device(e.g., a mouse or a trackball) by which a user can provide input to thecomputer system 1900. Other kinds of input devices 1914 can be used toprovide for interaction with a user as well, such as a tactile inputdevice, visual input device, audio input device, and/or brain-computerinterface device. For example, feedback provided to the user can be anyform of sensory feedback (e.g., visual feedback, auditory feedback,and/or tactile feedback), and input from the user can be received in anyform, including acoustic, speech, tactile, and/or brain wave input.Exemplary output devices 1916 include display devices, such as a cathoderay tube (CRT) or liquid crystal display (LCD) monitor, for displayinginformation to the user.

According to certain embodiments, a client device and/or a server can beimplemented using the computer system 1900 in response to the processor1902 executing one or more sequences of one or more instructionscontained in the memory 1904. Such instructions may be read into thememory 1904 from another machine-readable medium, such as the datastorage device 1906. Execution of the sequences of instructionscontained in the memory 1904 causes the processor 1902 to perform theprocess steps described herein. One or more processors in amulti-processing arrangement may also be employed to execute thesequences of instructions contained in the memory 1904. In someembodiments, hard-wired circuitry may be used in place of or incombination with software instructions to implement various aspects ofthe present disclosure. Thus, aspects of the present disclosure are notlimited to any specific combination of hardware circuitry and software.

Various aspects of the subject matter described in this specificationcan be implemented in a computing system that includes a back endcomponent (e.g., a data server), or that includes a middleware component(e.g., an application server), or that includes a front end component(e.g., a client computer having a graphical user interface and/or a Webbrowser through which a user can interact with an implementation of thesubject matter described in this specification), or any combination ofone or more such back end, middleware, or front end components. Thecomponents of the system 1900 can be interconnected by any form ormedium of digital data communication (e.g., a communication network).Examples of communication networks include a local area network and awide area network.

The term “machine-readable storage medium” or “computer readable medium”as used herein refers to any medium or media that participates inproviding instructions to the processor 1902 for execution. Such amedium may take many forms, including, but not limited to, non-volatilemedia, volatile media, and transmission media. Non-volatile mediainclude, for example, optical or magnetic disks, such as the datastorage device 1906. Volatile media include dynamic memory, such as thememory 1904. Transmission media include coaxial cables, copper wire, andfiber optics, including the wires that comprise the bus 1908. Commonforms of machine-readable media include, for example, floppy disk, aflexible disk, hard disk, magnetic tape, any other magnetic medium, aCD-ROM, DVD, any other optical medium, punch cards, paper tape, anyother physical medium with patterns of holes, a RAM, a PROM, an EPROM, aFLASH EPROM, any other memory chip or cartridge, or any other mediumfrom which a computer can read. The machine-readable storage medium canbe a machine-readable storage device, a machine-readable storagesubstrate, a memory device, a composition of matter effecting amachine-readable propagated signal, or a combination of one or more ofthem.

As used herein, a “processor” can include one or more processors, and a“module” can include one or more modules.

In an aspect of the subject technology, a machine-readable medium is acomputer-readable medium encoded or stored with instructions and is acomputing element, which defines structural and functional relationshipsbetween the instructions and the rest of the system, which permit theinstructions' functionality to be realized. Instructions may beexecutable, for example, by a system or by a processor of the system.Instructions can be, for example, a computer program including code. Amachine-readable medium may comprise one or more media.

As used herein, the word “module” refers to logic embodied in hardwareor firmware, or to a collection of software instructions, possiblyhaving entry and exit points, written in a programming language, suchas, for example C++. A software module may be compiled and linked intoan executable program, installed in a dynamic link library, or may bewritten in an interpretive language such as BASIC. It will beappreciated that software modules may be callable from other modules orfrom themselves, and/or may be invoked in response to detected events orinterrupts. Software instructions may be embedded in firmware, such asan EPROM or EEPROM. It will be further appreciated that hardware modulesmay be comprised of connected logic units, such as gates and flip-flops,and/or may be comprised of programmable units, such as programmable gatearrays or processors. The modules described herein are preferablyimplemented as software modules, but may be represented in hardware orfirmware.

It is contemplated that the modules may be integrated into a fewernumber of modules. One module may also be separated into multiplemodules. The described modules may be implemented as hardware, software,firmware or any combination thereof. Additionally, the described modulesmay reside at different locations connected through a wired or wirelessnetwork, or the Internet.

In general, it will be appreciated that the processors can include, byway of example, computers, program logic, or other substrateconfigurations representing data and instructions, which operate asdescribed herein. In other embodiments, the processors can includecontroller circuitry, processor circuitry, processors, general purposesingle-chip or multi-chip microprocessors, digital signal processors,embedded microprocessors, microcontrollers and the like.

Furthermore, it will be appreciated that in one embodiment, the programlogic may advantageously be implemented as one or more components. Thecomponents may advantageously be configured to execute on one or moreprocessors. The components include, but are not limited to, software orhardware components, modules such as software modules, object-orientedsoftware components, class components and task components, processesmethods, functions, attributes, procedures, subroutines, segments ofprogram code, drivers, firmware, microcode, circuitry, data, databases,data structures, tables, arrays, and variables.

The foregoing description is provided to enable a person skilled in theart to practice the various configurations described herein. While thesubject technology has been particularly described with reference to thevarious figures and configurations, it should be understood that theseare for illustration purposes only and should not be taken as limitingthe scope of the subject technology.

There may be many other ways to implement the subject technology.Various functions and elements described herein may be partitioneddifferently from those shown without departing from the scope of thesubject technology. Various modifications to these configurations willbe readily apparent to those skilled in the art, and generic principlesdefined herein may be applied to other configurations. Thus, manychanges and modifications may be made to the subject technology, by onehaving ordinary skill in the art, without departing from the scope ofthe subject technology.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is an illustration of exemplary approaches. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged. Some of the stepsmay be performed simultaneously. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

As used herein, the phrase “at least one of” preceding a series ofitems, with the term “and” or “or” to separate any of the items,modifies the list as a whole, rather than each member of the list (i.e.,each item). The phrase “at least one of” does not require selection ofat least one of each item listed; rather, the phrase allows a meaningthat includes at least one of any one of the items, and/or at least oneof any combination of the items, and/or at least one of each of theitems. By way of example, the phrases “at least one of A, B, and C” or“at least one of A, B, or C” each refer to only A, only B, or only C;any combination of A, B, and C; and/or at least one of each of A, B, andC.

Terms such as “top,” “bottom,” “front,” “rear” and the like as used inthis disclosure should be understood as referring to an arbitrary frameof reference, rather than to the ordinary gravitational frame ofreference. Thus, a top surface, a bottom surface, a front surface, and arear surface may extend upwardly, downwardly, diagonally, orhorizontally in a gravitational frame of reference.

Furthermore, to the extent that the term “include,” “have,” or the likeis used in the description or the claims, such term is intended to beinclusive in a manner similar to the term “comprise” as “comprise” isinterpreted when employed as a transitional word in a claim.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments.

A reference to an element in the singular is not intended to mean “oneand only one” unless specifically stated, but rather “one or more.”Pronouns in the masculine (e.g., his) include the feminine and neutergender (e.g., her and its) and vice versa. The term “some” refers to oneor more. Underlined and/or italicized headings and subheadings are usedfor convenience only, do not limit the subject technology, and are notreferred to in connection with the interpretation of the description ofthe subject technology. All structural and functional equivalents to theelements of the various configurations described throughout thisdisclosure that are known or later come to be known to those of ordinaryskill in the art are expressly incorporated herein by reference andintended to be encompassed by the subject technology. Moreover, nothingdisclosed herein is intended to be dedicated to the public regardless ofwhether such disclosure is explicitly recited in the above description.

While certain aspects and embodiments of the subject technology havebeen described, these have been presented by way of example only, andare not intended to limit the scope of the subject technology. Indeed,the novel methods and systems described herein may be embodied in avariety of other forms without departing from the spirit thereof. Theaccompanying claims and their equivalents are intended to cover suchforms or modifications as would fall within the scope and spirit of thesubject technology.

What is claimed is:
 1. A system for processing data representing acharacteristic of proteins, peptides, and/or peptoids, the systemcomprising: a data acquisition module, including a quantum cascade lasermicroscope, configured to: sequentially acquire spectral images of theproteins, peptides, and/or peptoids in a solution using the quantumcascade laser microscope without the use of exogenous probes oradditives, the sequentially acquired spectral images capturing inducedchanges in spectral intensities as a function of an applied controlledperturbation; identify and select, in at least one of the acquiredspectral images, a region of interest with respect to the appliedperturbation; and select and analyze spectral data including data forside chains of amino acids in the proteins, peptides and/or peptoids inthe solution for the region of interest in a plurality of thesequentially acquired spectral images, wherein analyzing the spectraldata includes analyzing side chain modes of the proteins, peptides,and/or peptoids as internal probes; and a correlation analysis moduleconfigured to: apply two-dimensional co-distribution (2DCDS) analysis togenerate an asynchronous co-distribution plot for the proteins,peptides, and/or peptoids; and identify in the asynchronousco-distribution plot a cross peak associated with aggregation of theproteins, peptides, and/or peptoids.
 2. The system of claim 1, furthercomprising a visual model generator for generating one or more plots fordisplay.
 3. The system of claim 1, further comprising a humaninteraction module comprising a human interface.
 4. Non-transitorycomputer-readable medium comprising instructions which, when executed byone or more computers, cause the one or more computers to: obtainsequentially acquired spectral images, taken using a quantum cascadelaser microscope, of the proteins, peptides, and/or peptoids in asolution without the use of exogenous probes or additives, thesequentially acquired spectral images capturing induced changes inspectral intensities as a function of an applied controlledperturbation; identify and select, in at least one of the acquiredspectral images, a region of interest with respect to the appliedperturbation; select and analyze spectral data including data for sidechains of amino acids in the proteins, peptides and/or peptoids in thesolution for the region of interest in a plurality of the sequentiallyacquired spectral images, wherein analyzing the spectral data includesanalyzing side chain modes of the proteins, peptides, and/or peptoids asinternal probes; apply two-dimensional co-distribution (2DCDS) analysisto generate an asynchronous co-distribution plot for the proteins,peptides, and/or peptoids; identify in the asynchronous co-distributionplot a cross peak that correlates with an auto peak associated withaggregation of the proteins, peptides, and/or peptoids; and use thecross peak to determine an order of a distributed presence of spectralintensities with respect to the applied perturbation.
 5. The system ofclaim 1, wherein the correction analysis module is further configured touse the cross peak to determine an order of a distributed presence ofspectral intensities with respect to the applied perturbation.
 6. Thesystem of claim 1, wherein the applied perturbation is a thermal,electrical potential, concentration, pressure, chemical, agitation,oxidation, or acoustic perturbation.
 7. The system of claim 1, whereinthe applied controlled perturbation is change in temperature over atemperature range.
 8. The system of claim 7, wherein the dataacquisition module is configured to sequentially acquire spectral imagesat regular temperature intervals.